Index: bin/expr/expr.1
===================================================================
--- bin/expr/expr.1
+++ bin/expr/expr.1
@@ -30,7 +30,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 5, 2016
+.Dd August 8, 2017
 .Dt EXPR 1
 .Os
 .Sh NAME
@@ -38,7 +38,7 @@
 .Nd evaluate expression
 .Sh SYNOPSIS
 .Nm
-.Op Fl e
+.Op Fl Ee
 .Ar expression
 .Sh DESCRIPTION
 The
@@ -67,6 +67,11 @@
 and with an error status.
 .Pp
 The
+.Fl E
+option enables interpretation of all regular expressions as extended regular
+expressions.
+.Pp
+The
 .Fl e
 option enables backwards compatible behaviour as detailed below.
 .Pp
@@ -275,7 +280,9 @@
 .Nm
 utility conforms to
 .St -p1003.1-2008 ,
-provided that backwards compatibility mode is not enabled.
+provided that backwards compatibility mode is not enabled and the
+.Fl E
+flag is not in use.
 .Pp
 Backwards compatibility mode performs less strict checks of numeric arguments:
 .Bl -bullet
@@ -307,8 +314,10 @@
 these arguments are treated just as their respective string values.
 .Pp
 The
+.Fl E
+and
 .Fl e
-flag is an extension.
+flags are extensions.
 .Sh HISTORY
 An
 .Nm
Index: bin/expr/expr.y
===================================================================
--- bin/expr/expr.y
+++ bin/expr/expr.y
@@ -41,6 +41,7 @@
 } ;
 
 char		**av;
+int		cflags;
 int		nonposix;
 struct val	*result;
 
@@ -275,14 +276,17 @@
 		av = argv + 1;
 		nonposix = 1;
 	} else {
-		while ((c = getopt(argc, argv, "e")) != -1) {
+		while ((c = getopt(argc, argv, "Ee")) != -1) {
 			switch (c) {
+			case 'E':
+				cflags |= REG_EXTENDED;
+				break;
 			case 'e':
 				nonposix = 1;
 				break;
 			default:
 				errx(ERR_EXIT,
-				    "usage: expr [-e] expression\n");
+				    "usage: expr [-Ee] expression\n");
 			}
 		}
 		av = argv + optind;
@@ -538,7 +542,7 @@
 	to_string(b);
 
 	/* compile regular expression */
-	if ((eval = regcomp(&rp, b->u.s, 0)) != 0) {
+	if ((eval = regcomp(&rp, b->u.s, cflags)) != 0) {
 		regerror(eval, &rp, errbuf, sizeof(errbuf));
 		errx(ERR_EXIT, "%s", errbuf);
 	}